This article on PC Gamers' website contains an interview with the lead designer for XCOM: Enemy Unknown, who speaks about there being differences such as higher resolution textures and a new user interface which displays "loads more data and allowing for a speed of interaction that changes how players approach tactical decisions" being available on the PC version in comparison to consoles.

Are there any other differences between the PC and console versions known at the moment, or any differences between individual console releases of the game?

It sounds like there is a pretty clear graphical difference.
–
RamhoundSep 17 '12 at 15:01

PC version also gets the tactical view grid and other things like that, but as mentioned there won't be a definitive list (and thus the question can't be fully answered) until closer to/after the release date.
–
kalinaSep 17 '12 at 15:02